| Frederick Engels. 1860s | 40-41 |
| Credentials of the General Council of the International written in Friedrich Sorge's name (in Marx's hand) | 59 |
| Marx's and Engels' correspondents: Paul Lafargue. Johann Philipp Becker, Friedrich Lessner, Ludwig Kugelmann. Georg Eccarius. Robert Applegarth. Nikolai Danielson | 104-05 |
| A sketch of Lizzie Burns by Frederick Engels (after 4 May 1869) | 145 |
| Karl Marx with his elder- daughter Jenny (end of December 1868-beginning of January 1869) | 200-01 |
| Marx's membership card of Land and Labour League (30 November 1869) | 376-77 |
| First page of Marx's letter to Laura and Paul Lafargue of 5 March 1871 | 447 |
| A page from the album of Marx's daughter Jenny with Frederick Engels' 'Confession' | 540-41 |